1. Field of the Invention
This invention relates generally to a clamshell lathe, and in particular to a mechanism for cutting, beveling, facing and boring the wall of a large diameter work piece.
2. Description of the Related Art
Clamshell lathes are known in the art. A clamshell lathe generally has a first and second semi-circular segment. The semi-circulars segments are clamped together to form an annular assembly encircling a work piece to be machined. The annular assembly includes a stationary ring, and a rotatable ring abutting the stationary ring. The rotatable ring is made of steel and has a spur gear on its peripheral surface and it is journaled on the bearings to the stationary portion for rotation about a concentrically disposed work piece. A motor drives a spur gear that meshes with the spur gear on the rotatbale right and that rotates the rotatable ring about the concentric work piece. A cutting tool assembly is mounted on the rotatable ring for machining the work piece.
The prior art cutting tools, however, have not adequately addressed the need for machining the work piece at an angle, such as may be required in creating a beveled edge on an end of the work piece. Moreover, the cutting tools have been able to incrementally advance in a radial direction against the work piece, the prior art advancing mechanisms incrementally advance the cutting tool upon every revolution of the rotatable ring of the clamshell lathe by the interaction of a star wheel with a stationary ring. The present invention dispenses with the star wheel arrangement and instead uses a tripper mechanism that allows control over the extent of radial displacement of the cutting tool relative to the workpiece being machined.